Prelims cum Mains Science & Tech

Glitch puts NASA’s Chandra telescope in ‘safe’ mode

The News

  • NASA’s Chandra X-Ray Observatory went into safe mode as a result of a possible gyroscope failure.



  • During the safe mode, scientific observations are interrupted.
  • The orientation of the spacecraft is changed so that the solar panels get maximum sunlight.


What do gyroscopes do?

  • In order to make precise observations of objects in space, pointing the telescope to an object and holding it steady is important
  • This job is done by the gyroscopes and steering devices called reaction wheels.
  • The gyroscopes help control the telescope’s pointing while scientists are observing the objects in space.
  • Further when the telescope needs to be re-pointed to another object, the gyroscopes sense this and pass this message to the computer control system.
  • The control system then a command to give the reaction wheels a “push” or “spin.”


About Chandra X-Ray Observatory

  • The temperatures in various objects in space like starts, galaxies, supernova, blackhole etc are extremely high to the order of 10^6 to 10^8 Kelvin.
  • Atoms in such a high-temperature gas move so fast that when they collide, they emit X-ray photons of very high energy and very short wavelengths less than 10 nm.
  • Thus to study hot objects like inside of a star, supernova, centers of galaxies etc X-Ray telescopes are necessary.
  • Further the X-ray photons in such short wavelengths do not enter earth because the earth’s atmosphere is opaque to them.
  • Thus X-ray telescopes designed to detect these photons must be placed in orbit above earth’s atmosphere.
  • X-ray astronomy took a quantum leap forward in 1999 with the launch of NASA’s Chandra X-ray Observatory.
  • Chandra is named after the Indian- American astrophysicist Subrahmanyan Chandrasekhar.
  • X rays are absorbed by mirrors and then reflected at a very shallow angle.
  • In this way X rays are focused onto a focal plane 10 m behind the mirror.
  • Thus Chandra can view the X-ray sky with an angular resolution of 0.5 arcsec wich gives sharp images of the object.

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